226 ^ Fertilisers [pt. hi, ch. xiii 



sour land, and the liability to scab is considered by some 

 practical men to increase after lime is applied, but more 

 definite experiments are needed on the subject. Rhubarb 

 does not usually benefit. 



Chalk should be applied as early as possible in autumn 

 so that winter frosts can disintegrate it and allow of a 

 better distribution later on by means of the harrow : it 

 is most conveniently applied to the leys. 



Even where limestone does not increase the jdeld of hay 

 or grass land it may improve the herbage : this happened 

 at Garforth, where sorrel was crowded out, and also in the 

 Lancashire trials, where the bent grass was practically 

 exterminated while the rye grass practically doubled. 



Many limestones contain magnesia and are therefore 

 considered to be risky in use ; the Newcastle Farmers Club 

 allows compensation for eight years for ordinary lime^ 

 but nothing for lime derived from magnesian limestone. 

 The experiments hitherto made in this country have 

 not justified this view nor have those at New Jersey^. 



Mortar rubbish contains considerable quantities of 

 calcium carbonate and should always be applied to gar- 

 dens whenever it can be obtained: it not only benefits 

 the soil but in virtue of its sand it helps the development 

 of fibrous root. 



Magnesian hme has proved useful on heavy soils 

 though it has sometimes given trouble on light land^. 



Gas lime may be used with advantage when it can be 

 obtained cheaply, but it should only be applied in 

 winter. The modern variety is less offensive than the 

 old fashioned "Blue Billy" but it is less useful as an 

 insecticide in horticultural work. 



* Durham Coll. Bull. No. 12, 1915. 



New Jersey Bulletin, No. 267, 1914. 

 See J. A. Hanley, Jo'irn. Soc. Chem. Ind. 191S, 18.5 T. 



